syzbot

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BUG: KCSAN: data-race in dequeue_signal / ptrace_check_attach

read-write to 0xffff888101eb36a8 of 8 bytes by task 21564 on cpu 0:
 dequeue_signal+0x3de/0x430 kernel/signal.c:685
 get_signal+0x37d/0x1080 kernel/signal.c:2790
 arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:310
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x59/0x130 kernel/entry/common.c:218
 do_syscall_64+0xda/0x1d0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888101eb36a8 of 8 bytes by task 25212 on cpu 1:
 ptrace_freeze_traced kernel/ptrace.c:189 [inline]
 ptrace_check_attach+0x7f/0x290 kernel/ptrace.c:256
 __do_sys_ptrace kernel/ptrace.c:1280 [inline]
 __se_sys_ptrace+0xd4/0x2b0 kernel/ptrace.c:1258
 __x64_sys_ptrace+0x55/0x70 kernel/ptrace.c:1258
 x64_sys_call+0x296f/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:102
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0x0000000008010000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 25212 Comm: syz-executor.2 Not tainted 6.9.0-syzkaller-08544-g4b377b4868ef #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
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